fuelup.lua

args = {...}
distance = args[1]
startFuel = turtle.getFuelLevel()

if distance == nil then
    print("Instructions:")
    print("- Place turtle next to a lava source")
    print("- Run \"fuelup [n]\", where n is distance to travel")
    print("- Have an empty bucket on hand to provide the turtle")
    print("- If starting from 0, put a lava bucket in to start the cycle")
    return
end

if os.getComputerLabel() == null then
    print("Your computer doesn't have a label!")
    print("Are you sure you want to start? [Y/n]")
    input = read()
    if input ~= "y" then
        print("Use \"label set [name]\" to add a name to your turtle so it retains its fuel when you pick it up!")
        return
    else
    end
end

while true do
    if turtle.getItemCount(1) > 0 and turtle.getFuelLevel() > 0 then
        turtle.refuel()
        print("Refueling for "..distance.." blocks...")
        break
    else
        if hasFailed == true then
            os.sleep(1)
        elseif turtle.getFuelLevel() == 0 then
            hasFailed = true
            print("Place lava bucket in slot 1...")
        else
            hasFailed = true
            print("Place empty bucket in slot 1...")
        end
    end
end

for i = 1, distance do
    turtle.forward()
    turtle.placeDown()
    turtle.refuel()
end

turtle.turnRight()
turtle.forward()
turtle.placeDown()
turtle.refuel()
turtle.turnRight()

for i = 1, distance do
    turtle.forward()
    turtle.placeDown()
    turtle.refuel()
end

turtle.forward()

fuelGain = turtle.getFuelLevel() - startFuel

print("My fuel level is "..turtle.getFuelLevel()..", and I gained "..fuelGain.." on my trip!")
print("Refueled Successfully!")